Solenoid



March 15, 193s. f A, WETZL t 2,11,232

SOLENOID Filed Aug. 28, 1957 JWM/'MMA WLJP/ i@ ME E PatentedMan 15, 1938 PATENT OFFICE SOLENOID Theodore A. Wetzel, Milwaukee, Wis., assigner 'to Milwaukee Gas Specialty Company, Milwau- Akec, Wis., a corporation of Wisconsin Application August 28, 1937, Serial No.. 161,42l.

SClaims.

This invention relates to electromagnets and refers particularly to the solenoid type of electromagnet designed to operate'valves and kindredzapplianees.

The attainment of quietness in operation has always been a problem, particularly where the solenoid is of the single phase alternating cur- ,rent type. 'Ihe constructions heretofore proposed for this purpose have been objectionable from the standpoint of requiring an excessive number of parts, and also for the reason that they did not provide against noise resulting from lateral motion o the armature.

It is therefore an object of this invention to Y provide quiet operation for a solenoid of the character described with a minimum number of parts.

Another object of this invention resides in the provision of means whereby lateral play ybetween Y the armature and its guideway is positively taken up to preclude noise arising -irom this cause.

Another object of this invention vis lto provide means whereby the shading ring on the armature splits the phase of the magnetic flux to further guard against chattering.

Another object of this invention is to provide a construction whereby the eiects' of residual magnetism in the armature are vitiated to prerclude the armature being held against its normal m motion consequent to the deenergization of the magnet coil. Y

' A further object of this invention is to provide a solenoid which is particularly applicable for use with valves, and especially gas valves.

With the above and other objects inview which will appear as the descriptionproceeds, this invention resides in the novel construction, combinaidon and arrangement of parts substantially as hereinafter described, and more particularly delined by the appended claims, it being underf stood that suchschanges in the precise embodiment of the hereindisclosedinvention may be` made as come within of the claims.

The accompanying drawing illustrates one complete'example of the physical embodiment of the invention constructed according to the best mode so far devised furthe practical application of the principles thereof,V and inV which:

Figure l is a longitudinal sectional view through a valve equipped with the solenoid of this invention illustrating the same in its deenerg'lzed condition; Figure 2 is a :longitudinal sectional view through the armature per se; u Flgure3isacrosssectionalviewthroughthe armature taken on the plane of the iine 3-3 of Figure 2; and

Figures 4 and 5 are enlarged sectional views through the armature and its guide tube illustrating the manner in which its unbalanced mass 5 on a transverse Vplane causes the magnetic pull A of the coil to hold the same against one, side of the tube.

Referring now particularly to the accompanying drawing in which like numerals indicate like 10 parts, the numeral 5 designates a guide tube of non-magnetic material closedat its upper end by a plug 6 of magnetic metal and having a plunger type amature 'l slidable therein. A magnet coil 8 surrounds the upper end portion 15 of the tube 5, which, upon energization, draws the armature upwardly toward the plug ,6.

The upward attraction imposed on the armature upon Venergization of the coil is augmented by a magnetic sleeve 5' which surrounds the upper end of the tube 5; and to further improve the eiciency of the solenoid and reduce the wattage consumption, an iron shell is attached to the sleeve 5' and encloses the coil with its lower end in Contact with an iron washer i0. Hence, upon energization of the coil 8 the ilux flows through the shell and the washer, which, lying close to the amature, provides a short path to the armature and thus reduces the wattage required to lift the armature. 30

In the present instance where the solenoid is used with a gas valve, the upward motion of the armature lifts a valve 8 ofi its seat, the seat being located between the inlet and outlet of the to the underside of the cover also fasten the magnetic washer I0 to the cover. 45

'Ihe valve 9 comprises a valve disc having a leather face Il loosely secured to the lower end of a non-magnetic stem I5 which is slidably received in a bore I6 extending longitudinally through the center of the armature. The stem 50 j l5 is longer than the armature and has a non- Y magnetic head I1 on its upper end to be engaged Y by the upper end oi the armature with a hammer-like blow upon response ofthe armature to enersimtion of the coil.

A recess I8 in the undersurface of the magnetic plug 6 accommodates the head I1 of the valve stem and permits the amature to engage the lower edge of a non-magnetic spacer collar I9 secured in the recess I8.- The spacer projects down below the bottom of the plug 6 to hold the armature from actual contact with the plug and thereby preclude residual magnetism of the armature from holding the valve open after deenergization of the Coil.

As best shown in Figures 4 and 5, the armature consists substantially of a cylinder of magnetic metal having a plurality of longitudinal flutes or grooves 20 cut therein at spaced intervals extending partially around the circumference of the cylinder. vThese utes or grooves form the cross section of the armature into a small diameter cylinder having a plurality of radial circumferentially spaced ribs 2I extending longitudinally throughout the length thereof with a portion 22 f of substantial mass disposed at one side of the axis of the armature.

This unbalanced or eccentric distribution of the mass in the plunger gives the same a low magnetic reluctance at its side having the portion 22 so that upon energization of the coil the armature not only rises to enter'the enclosure defined by the magnetic sleeve 5, but is also drawn sdewise to be held against the inner surface of the guide tube 5 and thus preclude the armature from wandering and rattling in its guide tube.

Near its upper end the armature is encircled by a shading ring 23 of copper or other suitable metal. It appears possible that the shading ring, being positioned as it is, aids the magnet coil in maintaining the armature tightly against the spacer collar I 9.

Four factors of the construction as described thus coact to produce an efficient and quiet solenoid. They are-the magnetically unbalanced armature; the shading ring carried by the armature; the magnetic sleeve; and the magnetic plug at the upper end of the guide tube. The magnetic sleeve extends down into the coil a substantial distance so that a considerable part of the armature is telescoped into it, thus giving the mags netically unbalanced formation of the amature maximum effectiveness.

The shading ring, being located where it is, also serves to split the phase of the magnetic flux. `T'his follows from the fact that when the armature is in its raised position, the shading ring lieswithin the confines of the sleeve 5. 'Ihe ux flowing from the sleeve 5' to the armature is thus split by the presence of the shading ring causing 'a part thereof to lag behind the rest. The advantages of multi-phase current are thus achieved to a degree.

From the foregoing description taken in connection with the accompanying drawing, it will of the plunger has a lesser magnetic reluctance than other portions thereof.

, 2. A solenoid comprising: a coil; guide means disposed within the coil; a rigid amature movable within the coil and snugly but slidably engaging said guide means, said armature having both its ends lying in planes substantially normal to the central longitudinal axis of the armature and having its magnetic mass unsymmetrically distributed with respect to said axis with considerably greater magnetic mass on one side of a plane parallel to the line of motion of the armature and including the axis of the coil than on the opposite side thereof so that the magnetic reluctance at one side of the armature is greater than at other portions thereof; and stationary magnetic means alongside the armature and cooperating therewith whereby the armature is held laterally against the guide means upon energization of the coil.

3. A plunger type armature for electromagnets comprising: substantially a cylinder of magnetic metal having a plurality of longitudinal flutes to give the plunger a ribbed cross sectional shape. said flutes being so circumferentially spaced that at least one of the ribs is substantially wider than the rest so that the plunger has greater mass at one side of its axis than at the opposite side to provide a path of lesser reluctance at said rst side of the plunger. v

4. A solenoid construction of the character described comprising: a tube of non-magnetic metal; a magnet coil surrounding the tube; a magnetic sleeve surrounding the tube within one end portion of the coil; a plunger type armature slidable in the tube, said armature having guide ribs extending radially therefrom for contact with the inner wall of the tube and having a portion of substantial mass and considerably wider than the guide ribs disposed at one side o! its axis to provide a path of low magnetic reluctance so that upon energization of the coil the magnetic pull exerted through the magnetic sleeve holds the armature against the inside surface of the tube.

5. A solenoid construction of the character described comprising: a tube of non-magnetic material; a magnet coil surrounding one end portion of the tube; a magnetic sleeve surrounding the tube within one end portion of the coil: a plug clomng said end of the tube and formed of magnetic metal; a plunger type armature slidable in the tube toward the magnetic plug and into the magnetic sleeve upon energization of the coil. said armature having circumferentially spaced longitudinally extending ribs projecting radially therefrom, one of said ribs having a substantially greater width than the others so as to provide a portion of substantial mass at one side of the axis of the armature whereby said side of the armature has lesser magnetic reluctance than other portions thereof so that the armature is drawn rmly against the inside surface of the tube by the magnetic pull exerted through the magnetic sleeve upon energimtion of the coil: non-magnetic spacer means for holding the armature out of contact with the magnetic pim: and ashadingringendrclingthearmaturenear its end which moves into the magnetic sleeve.

6. A solenoid comprising: a magnet coil; a rigid armature; guide means to limit the motion .of the amature substantially to movement axially of the coil; a stop against which the amature is moved upon energization of the coil; a magnetic sleeve within one end portion of the coll. 15

arranca said magnetic sleeve being shorter than the coil but long enough to receive at least a portion of the amature `as it engages said stop; said armature having both its ends lying in planes substantially normal to the central longitudinal axis oi the armature and having its magnetic mass unsymmetrically distributed with respect to said axis with considerably greater magnetic mass on one side of a plane parallel to the line of motion of the armature and including the central longitudinal axis of the magnetic sleeve than on the opposite side thereof so that one side of the armature has considerably less magnetic reluctance than other portions thereof; whereby the armature is attracted laterally toward the magnetic sleeve to take up all play between the armature and its guide means.

il. A solenoid comprising: a magnet coil; a rigid armature; guide means to limit the motion oi the armature substantially to movement. axially of the coil; a stop located to be engaged by the armature upon movement thereof in responseto energization of the coil; a magnetic sleeve within one end portion of the coil, said magnetic 'sleeve being shorter than the coil but long enough to receive at least a portion of the armature as it engages the stop, said armature having both its ends lying in planes substantially normal to the central longitudinal axis of the armature and having its magnetic mass unsymmetrically distributed with respect to said axis with considera'oly greater magnetic mass on one side of a plane parallel to the line of motion of the armature and including the central longitudinal axis of the magnetic sleeve than on the opposite side thereof so that one side of the armature has con.- siderably less magnetic reluctance than other portions thereof whereby the armature is attracted laterally toward the magnetic sleeve to take up all play between the armature and its guide means; and a shading coil encircling that portion ci the amature which moves into the rnagwhich the armature is constrained to motion aarially through the coil and into said magnetic sleeve; a magnetic stop within the magnetic sleeve lout spaced therefrom ior limiting the motion of the armature in response to energization of the coil; non-magnetic means for spacing the armature from said stole, the armature having both its ends lying in planes substantially normal to the central longitudinal axis of the armature and having its magnetic mass unsymmetrically distributed respect to said axis with considerably greater magnetic mass on one side of a plane parallel to the line of motion of the armature and including the central longitudinal axis of the magnetic sleeve than on the opposite side thereoi so that one side oi the armature has consid-- era'oly less magnetic reluctance than other portionsv thereof whereby the armature is drawn laterally toward the magnetic sleeve' to maintain the same in rm engagement with its guide tube; and a shading coil carried by and encircling the armature at a point so spaced from the end of the armature which enters the magnetic sleeve that the shading ring lies loetween the ends of the magnetic sleeve when the armature contacts its stop.,

TIELEUDORE A. WETZEL. 

